Process and apparatus for separating liquids from solids



G. H. ANDERSSON Feb. 23, 1932. 1,846,076 PROCESS AND APPARATUS FORSEPARATING LIQUIDS FROM SOLIDS 2 Sheets-Sheet 1 Filed Sept. 1'7, 1930wwewroe G'm /a r fi ar y %zm er.ssolz Feb. 23, 1932. H. ANDERSSON1,846,076

PROCESS AND APPARATUS FOR SEPARATING LIQUIDS FROM SOLIDS Filed Sept. 17.1930 2 Sheets-Sheet 2 Patented Feb. 23, 1932 UNITED STATES PATENT OFFICEGUSTAV HARRY. ANDERSSON, OF STOCKHOLH, SWEDEN, ASSIGNOR TO THE DE LAVALSEPARATOR COMPANY, OF NEW YORK, N. Y A. CORPORATION 01 NEW YORK PROCESSAND APPARATUS FOR SEPARATING LIQUIDS FROM SOLIDS Application filedSeptember 17, 1930, Serial No. 482,414, and in Sweden Iarch 5,1980.

In centrifuges for continuous separation and removal of solid mattersfrom a liquid, or for continuous separation and removal of solid mattersfrom liquids of difierent specific gravities which are themselves continuously separated and removed, it is known to introduce a flushing liquidinto the bowl, preferably in the vicinity of the solids discharge, tofacilitate the removal from the bowl of the solids or to reduceloss ofthe sep-l the following description, in the course of.

which reference will be made to the devices for carrying out my newprocess illustrated in the drawings, in which- Fig. l is a verticalsectional View of the centrifugal bowl which .it is preferred to use incarrying out the process.

Figs. 2, 3, 4t and 5 are vertical sectional views, more or lessdiagrammatic, of different devices for regulating the inflow of flushingfluid relative to the outflow from the bowl of solids and liquid.

Fig. 6 is a vertical sectional view of a mod ified construction ofcentrifugal bowl.

In the centrifuge shown in Fig. 1 the mixture to be separated, which maybe assumed to comprise two liquids of different specific gravities andsolid matters (including sludges other than solids, of high specificgravities) is fed through the tube 1 into the central receiving chamber2, whence it is conducted, through openings 3, into the separatingchamber of the bowl. The bowl may contain a liner of frusto-conicaldiscs 4 con taining orifices aligning with opening 3, the enteringmixture flowing up through the orifices in the conical discs and beingthereby distributed through the spaces between the discs. Thelighterliquid moves toward the center of the bowl and discharges through anopening in the upper end of theneck of the topdisc. Theheavier liquidmoves toward the periphery and outflows through a channel '6 between thetopdisc and. the bowl wall and discharges through an opening at with thesolid matters, of a very considera 1c proportion of the heavierseparated liquid cannot be avoided.

It is known to introduce into the bowl either along with the mixture tobe separated, or (much preferably) through an independent feed channelopening adjacent the periphery and preferably-adjacent the openings 10,a flushing liquid or addition 1i uid to aid in expelling the solidsthrough t e openings 10. By this expedient, the openings may be madelarge enough to avoidclogging. See British patent to AktiebolagetSeparator et al., N 0. 10,314. of 1908; The expedient, however, isnotoperative, in most cases, to prevent the heavier liquid constituentof the original mixture from escaping with the solids and flushingliquid, or to prevent the admixture with and outflow of some of theflushing liquid with the separated heavier liquid constituent of theoriginal mixture.

Instead of introducing-the flushing liquid into the separating space ofthe bowl, it is introduced into a chamber or chambers outside of, andwhich may or may not entirely surround, the separating space of thebowl; said chamber communicating with the openings 10 and also havingopenings communicating with an outside receiving chamber. This specificc amber, which itv is preferred to use, i

has outer walls which, in vertical cross-section, converge, from theouter-openings '14, toward the sloping walls of the separating chamber.The flushing liquid is introduced through a fixed tube 12 and channel 13into the chamber 11. The flushing liquid streams out with the solidsthrough openings 14.

If the supply of flushin liquid through tube 12 is equal to the out owthrou h the openings 14, there will be no outflow o heavier separatedliquid from the. separating chamber of, the bowl through the openings 10and only the heavier solids will pass through these openings; and therewill be no inflow of flushing liquid into the sludge space 8.

Hit is of primary importance to prevent Y flushing liquid from streamingthrough openings 10 into sludge space 8 and therein becoming mixed withthe heavier separated liquid,

the volume of inflow of flushing liquid through tube 12 is maintainedsomewhat below the volume of outflow of flushing liquid and solidsthrough openings 14, which results in a slight flow of seperated liquidthrough openings 10 into chain erllj sufiicient to prevent 'nflow offlushing liquid through openings 0 into sludge space 8.

If it is of primary importance to prevent any loss of the separatedheavier liquid, the volume of inflow of flushing liquid through tube 12is maintained somewhat above the 1 volume of outflow of flushing liquidand solids through openings 14, which results in a slight flow offlushing liquid through openings 10 into sludgespace 8 suflicient toprevent outflow of the separated heavier liquid through openings 10 intochamber 11.

There are, however, various factors WlllCh make it diflicult topredetermine with exactness the rate of inflow of flushing liquidrequired to insure against either, on the one hand, outflow of separatedheavier liquid or,

on the other hand, inflow of flushing liquid through openings 10. It isstill more difiicult to so nearly balance the inflow through tube 12 andthe ouflow through openings 14 asto substantially prevent any flow ofeither liquld through openings 10.

If, for example, the number of R. P. M. of

the separator bowl is changed, or if the size of the outflow openings ischanged, as, for example, if their size be increased by wear, thedirection of liquid flow through openings 10 may be the reverse of thatdesired. Then again the percentage of solids in the liquid mixture andthe rate at which the solids flow into the chamber .11 may Vary, whichmay also result in an undesired reversal of flow and in an upsetting ofthe desired balance be tween inflow of flushing liquid to, and outflowof solids and liquid from, chamber 11.

An important object of the invention is to ma'intain such balance as maybe desired between the inflow of flushing liquid to chamber 11 and theoutflow therefrom of solids and liquids, including the maintenance, whendesired, of substantial equality between such inflow and outflow so asto recover the solids substantially free of separated heavier liquid andrecover the separated heavier liquid substantially free of flushingliquid.

Referring, first, to Fig. 2: The liquid :streaming out throu h theopenings 14 is collected and flows t rough a pipe line. 15 into acontainer 17 providedwith an outlet opening 16. Container 17 is providedwith a float 18 the movements of which are transmitted, through a lever19, to a valve 21 in the supply pipe 20, which connects with tube 12.With the flow through the tube 15 varies the level in the container 17and the position-of valve 21.- By suitably constructing and adjustingvalve 21, the relation between the quantities of liquid per time unitflowing through the outflow tube 15 and the inflow tube 20 may bemaintained constant, or a-predetermined excess of flow may be maintainedthrough either pipe 15 or pipe 20.

It is assumed that the pressure in the supply pipe 20 ahead of the cook21 isconstant. If this be not the case and if it is diflicult to providea reduction valve before the valve 21, the supply may be regulated asshown in Fig.8. A container 22, similar to container 17, is suspendedfrom one end of a a lever 23 turnable, betweenits ends, on a pin 24.Suspended from the other end of said lever isanother similar container25 whose bottom outlets connect with a pipe 26. u The addition liquid issupplied to the container 25 through 'pipe 27 and discharges throughpipe 26 and tube 12 into the centrifuge. In the pipe 27 is a valve 28which is connected, by a link 29 and an arm 30, with the lever 23. Iffor any reason the quantity streaming out through the openings 14 in thewall of the centrifugal bowl increases, th level in the container 22rises and the container 22 thereby becomes heavier and sinks. By

means of the"lever23 and the link 29 the container acts on the valve 28to more fully the container 32 wherein the level will vary with the rateof inflow of such liquid. As the float 33 in the container rises orfalls, it raises or lowers respectively the movable part 34 of thesupply pipe 35 for flushin liquid. From the part 34 the flushing liquistreams out into a supply container 36, and a float 37 therein regulatesthe supply from the part 34 in such way that the level in the containerfollows the movements of the part 34 and thus also the variations of thelevel in the container 32. The outstream through the opening 38 willthus depend on the outstream through the openings 14 in the centrifugalbowl. From the container 36 the flushing liquid is fed through a pipeline 39 and tube 12 into the centrifugal bowl. The conjunction betweenthe amount of flushing liquid fed into the centrifuge and the an amountof liquid streaming out through the openings 14" can be regulated bymeans, for instance of a valve in the discharge openin es/ It isnot'necessary that the movable part V 2a 34 shall be connected with theother part 35 g of the supply pipe by means of a hose 40, as shown inFig. 4. Fig. 5 shows an alternativ'e arrangement by means of which thesame result may be obtained. The movable part of the supply pipe 41comprises a tube '42 movably arranged in the supply pipe and cdlmectedwith the float 33 in the container 32 by means of an arm 43 and a rod44.

In all the arrangementshereinhefore described, which are merelyillustrative of many possible embodiments of my invention, theregulating devices are controlled by vari ions in the quantity of liquidin the cont iner in which the liquid: is collected when it streams outfrom the centrifugal bowl, but variations in the specific gravity ofsuch liquid can be utilized to eiiect the desired regulation. If thespecific gravity of the separated liquid is different fromthat 45 of theflushing liquid, the specific gravity of the liquid in the container ischanged if a quantity of such heavier separated liquid enters thechamber 11 through the holes 10 and is mixed with the flushing liquid.

This change in the specific gravity of the liquid in thecontainer can beutilized'for rendering the regulating device operative.

The centrifugal bowl herein described is intended for separation ofsolids from a mixture of liquids but vice according to the presentinvention can, of course, also be used in connection with centrifugesintended for the separation of solids from a homogeneous liquid.

to In Fig. 6 the chamber 11 of the separator bowl is shown as providedwith adjustable outlets 50 for the flushing liquid. These outlets may bearranged as level outlets, the edges of which nearer the rotation centerof the bowl being adjustable in a radial directhe regulating detion. Ifthe outlets are moved toward the rotation center the pressure of theliquid at the openings 10 and 14 increases. If the outlets are movedoutward the opposite efl'ect is roduced. It is desirable to avoid lossof quid by outflow through outlets 50, and to provide a stationary rinof liquid the inner level of which is limited y the outlets.

To substantially prevent this outflow/or "limit it to a minimum, theliquid discharged -through outlets 14 is carried, as above described,through pipe 15 into the container 17 of Fig. 2; while any flushinliquid discharging through outlets 50 is fed to the same containerthrough another pi e 51. Alternative'ly, the li uid from out ets 14 and15 may be collecte in a common receiving vessel and conveyed through apipe (15 or 51) ,to container 17. The quantity of flushing liquidintroduced into the bowl with this ar-:

rangement is determined not merely by the amount of liquid dischargedthrough outlots 14, but, in addition thereto, by the amount ofliquidescaping through outlets 50.

The liquidescapin throughout outlets 50 may also be conveye to thecontainer 22 of Fig.3, or'tothe containers 32 of Figs. 4 and 5; and anyof the arrangements of Figs. 3, 4 or 5 will function in the mannerhereinbefore described, with the additional advantage of minimizing lossof liquid.

What I claim is: 1. The process of separating liquids from solid matterswhich com rises subjecting'a mixture thereof to centrifugal force andeffectin a substantial separation of the liquid from the solids andseparately outflowin the .separated constituents, conveying a flus ingliquid to the locus of centrifugal force and discharging it with theseparated solids, and regulating the rate of supply of flushing liquidin accordance with the rate of outflow ofthe flushing liquid and .solidsfrom the locus of centrifugal force. I v

2. The process of separating li uids from solid matters which comprisesslilljecting a mixture thereof to centrifugal force and effectinga'substantial separation ofthe liquid from the solids, separated liquidfrom thelocus of separation, separately dischar 'ng the separated solidmatters. from the ocus of separation while maintaining them undercentrifugal force, conveying a flushing liquid to the locus of theseparated solid matters, discharging the flushing liquid and separatedsolid" matters from the locus of separated solid matters,

and regulating the rate of supply of flushing separately discharging theoutflow there and a peripheral sludge outlet, of a conduit for supplyinflushing liquid to the vicinity of said slu ge outlet, and meanscontrolled by the rate of discharge from said outlet to regulate therate of supply of flush: ing liquid.

4. A centrifugal apparatus comprising a rotatable bowl having an inletfor a mixture to be separated, an outlet for separated liquid, and asludge-receiving peripheral space having-inner openings communicatingwith the interior of the bowl and outer discharge openings, a conduitfor supplying flushing liquid to said peripheral space, and meanscontrolled by the rate of discharge through said peripheral space toregulate the rate'of inflow of flushing liquid into said peripheralspace.

5. A centrifugal apparatus comprising a rotatable bowl having an inletfor a mixture to be separated, an outlet for separated liquid, and aperipheral sludge outlet, of a conduit for supplying flushing liquid tothe vicinity of said sludge outlet, a tank adapted to receive thedischarge fromthe sludge outlet and provided with an outlet, a float inthe tank, a conduit for supplying flushing liquid to the vicinity ofsaid sludge outlet, and means controlled by said float to control theflow of flushing liquid into the bowl.

6. A centrifugal apparatuscomprising a rotatable bowl-having an inletfora mixture to be separated, an outlet for separated liquid, and asludge-receivingperipheral space having inner openings communicatingwith the interior of the bowl and outer discharge openings, a conduitfor supplying flushing liquid to said peripheral space, a tank ada tedto receive the discharge from the slu ge outlet and provided with anoutlet, a float in the tank, and means controlled by said float tocontrol the flow of flushing liquid into said peripheral space.

In testimony of which invention, I have hereunto set my handatStockholm, Sweden, on this 29th day of August, 1930.

GUSTAV HARRY ANDERSSON.

